We got these shots of Tom pulling up to their place Thursday morning in L.A.'s San Fernando Valley, and he was riding solo, which has become the norm for him since the "Scandoval" broke.

It's a pretty good indication of what life is like for Tom now -- Ariana wasn't home, she's off in New York City for work and play, hanging with her new bae and doing a media blitz about Tom with several outlets.

We're told Tom appeared somber and in low spirits Thursday morning and his only companion was the guy helping him unload music equipment ... who might just be an Uber driver.

He and his band have been touring in Texas, but they don't have another gig until next week in Illinois -- so, lots of time to sit and think. For better or worse.

As we reported ... Ariana went on "Watch What Happens Live" Wednesday night and cast doubt on reports of a breakup between Tom and Raquel Leviss. Ariana says Raquel sent a letter earlier this week to the house. It was for Tom, not Ariana.

Maybe Raquel's letter will brighten Tom's mood ... unless it was a breakup note.

TMZ broke the story ... Tom and Ariana are still living in the home they share together despite his affair with Raquel, but they're sleeping in different rooms and are rarely there at the same time. Never been a better time for them both to be busy!